Some mobile devices, such as mobile devices operating in 3G networks, are running an increasingly large number of applications. Furthermore, in true multi-tasking environments, these applications are running simultaneously, and may introduce their own timers for various purposes, e.g. polling or keep-alive. These timers, in conjunction with regular user activity, result in an increased number of short data transmissions.
To transmit data, a data connection must exist. If it does not exist, then it must be established, for example a PS RAB (packet switched radio access bearer). There is a signaling protocol associated with data connection establishment. When there is no more data to transmit, the data connection is released. There is also a signaling protocol associated with data connection release. The establishment and release of the data connection takes time, for example about one second or more in some implementations.
When the radio wakes up, for example for periodic/non-periodic network service events, or for timer based periodic/non-periodic background application data transmission, it is entirely possible that immediately after the device goes back to idle, another event requiring the radio to wake up could occur. The result is increased radio activity, using more power as the connection needs to be setup again immediately.
Examples of applications that might perform background polling include Facebook™, Twitter™, and WeatherEye™. Another example of non-user initiated polling is the keep-alive/ping transmissions that take place for always-on applications or devices. Such devices may have an always-on PDP (packet data protocol) context. The mobile device uses a keep-alive/ping mechanism to prevent the PDP context from being closed by the network.